Mass Effect Andromeda Defeating The Kett is an optional mission that is added to your log during early story quest A Better Beginning, but is worth holding off on until much later in the game due to its difficulty.
The mission takes the form of a protracted assault on a heavily fortified base filled with a lot of high-level enemies, so we'd recommend being at least level 30 and owning high-tier weapons and armour before taking it on.
If you're after help for parts of the game, consult our Mass Effect Andromeda walkthrough and guide.
Defeating the Kett
Note: at time of writing this quest suffers from an intermittent glitch; if you get caught by it it's still possible to complete the mission, it will just be more difficult than it was designed to be.
Once you feel ready to tackle it, gather your squad together and make your way to the marker - we'd recommend Cora and Drack as she comes in handy to keep your shields up, and he's useful for clearing a path.
When you reach the dome eliminate the enemies outside the front door, interact with the terminal on the left, and then hold your position while SAM slowly hacks the security system - enemies will continue to spawn even after the door unlocks, so as soon as SAM is finished head inside and ignore the survivors.
Once inside the base you'll be constantly assailed from all directions by Kett of every description. Cover is limited so your best bet is to keep moving - attempting to hold your ground will just result in you being flanked and torn to shreds. Use the terminals around the ringed walkway to drop the shields, and then deal with the alarm.
(This part of the quest may not work correctly; if, after turning off the alarm, it continues to sound and the objective doesn't clear just ignore it and carry on. You'll have to deal with more enemies than intended, but it is winnable!)
Once the alarm is off you'll have three more terminals to interact with. A tactic of sprinting and leaping your way to each may prove more effective than trying to fight towards them - if you move quickly enough you may be able to get to one or two of them before enemies spawn near each one meaning you can activate them in relative safety.
Want more help? Our Mass Effect Andromeda walkthrough and guide provides steps to completing every main mission, and our on-going Remnant Decryption puzzle solutions can help with the many Sudoku-like challenges the game can throw at you. Meanwhile, we can help with Memory Trigger locations, Architect locations and the hidden Fusion Mod of Adrenaline, as well as helping you decide on the many Mass Effect Andromeda Romance options for both male and female Ryder.
Your next objective is on ground level at the rear of the facility. Activate the terminal against the far wall and then move forward into the chamber ahead.
You'll now be facing off against a hoard of Kett along with an Invictor, another variant of the Cardinal. He will target you rather than your squad, so leave them to deal with the smaller enemies while you take down the boss - destroy his shield orb, deal as much damage as you can before it recharges, and repeat.
Once the boss is down the other enemies finally stop spawning, so eliminate any remaining Kett and then head into the next room. Use the elevator to reach the lower level, use the console near the far window to finish the quest, and loot the containers on your way back out.